Modulated oscillator



May 3l, 1932.

LIE

7- Z41LP/ r F. J. MEADE MODULAT ED OS C I LLATOR Filed Oct. 5. 1929 Patented May 31, 1932 PAIE NT oi-"Flce FRANCIS J. MEADE, or KNoXvILLE, TENNESSEE, AssIcNon or ONE-HALF To vAnctrsrus GUMPERT, or WASHINGTON, DISTRICT on COLUMBIA MODULATED OSCILLATOR Application led october 3, 1929. Serial No. 397,117.

This invention relates to a modulated oscillator, and has forone of its objects to provide a novel and simple apparatus of this4 character that may be used as a calibrator or as a tester for radio receiving sets and that may be used in connection with a radio receiving set for the purposer of transmitting signals.

The invention is hereinafter fully described a-nd claimed and illustrated in the accompanying4 drawings, wherein Figure'lV is a diagrammatic view of the apparat-us, and Y Figure 2 is a diagrammatic view of the apparatus and an amplifying unit therefor.

The apparatus comprises an oscillator 1, which consists of a three-element vacuum tube, a transformer 2 which consists of three closely coupled coils, and controller 3 which may consist of a telegraph key or `a microphone.

The iilament 4 of the oscillator lis connected by leads 5 to the'secondary coil 6 of an alternating current or power transformer f 7 The plate 8l of the oscillator is connected by a lead 9 to the coil 10 of the transformer 2, and t-he grid 11 of the oscillator is connected by a lead l1 to the coil 12 of the transformer. The leads 9 and 11 are con- 3U nectedl to opposite or remote ends of the coils and 12, and the other ends of these coils are connected by leads 13 and 14 to a B-battery 15.

The resistance element 16 of a potentiometer is connected across the leads 5, and the movable contact 17 thereof is connected by a lead 17a to the lead 14. A by-pass condenser 18 is connected across the leads 13 and 14 and a variable condenser 19 is connected across the leads 11 and 17a. A choke coil 20 is connected in the lead 13 between the battery and condenser 18.

The controller 3 has its key or microphone 21 connected by leads 22 to the terminals of the secondary coil y23 of the transformer 2. A variable condenser 24 is connected in one of the leads 22.

The apparatus, as thus far described, may be used as a tester or a calibrator or may be used in connection with a receiving set for the purpose of transmitting signals. 'The plate circuitv and thegrid circuit include the reversely connectedprimary coil `10 and the tuning coil 12, respectively, with the result that the oscillations surging in the plate circuit will set up oscillations in the grid circuit. The plate and grid, circuits also include the loop which consists of the leads 13 and 14, battery 15, condenser 18 and choke coil 20. rIhe oscillations surging in the plate and grid circuits set up oscillations. in the controlling circuit which includes. the secondary coil 23, the microphone 2l or interrupter and the condenser 24. The operation of the microphone or interrupter modifies the oscillations in its circuit,.and corresponding modifications take place in the oscillations in the plate and grid circuits. These oscillations surge in the loop, radiated from the loop, the resulting electric waves impinging on the receiving set to which the apparatus is tuned by the adjustment of the condenser 19, and corresponding electric waves will emanatefrom the antenna of the receiving set.

If desired, one or more amplifying units 'l may be used in connection with the apparatus, as shown in Figure 2 and designated 25. When the amplifying units are employed, a transformer 26 is used in place of the choke coil and is connected to the units by leads 27. If desired, an A-battery may be used in place of the alternating current source. The apparatus has been tested and it may be used in connection with any of the well known receiving sets now on the market. To adapt it for userin connection with any particular radio receiving set, it is only necessary to tune it to the set, and it operates without direct electrical connection with the set. It ischaracterized by a controlling circuit in which oscillations are set up by the oscillations in plate and grid circuits, this resulting from the close coupling of the controlling circuits secondary coil with the primary coil of the plate circuit and tuning coil of the grid circuit.

Vhile I have described the principle of the invention, together with the structure which I now consider the preferred embodiment.

and their energy isV thereof, it is to be understood that the structure shown is merely illustrative and that such changes may be made, When desired, as fall Within the scope of the invention as claimed. All of Ythe condensers may be of the fixed or variable type as desired.

I claim l. A'niodulated oscillator and anoutpuvt circuit therefor, including a three element audion tube, an absorption circuit containing an absorption coil, two coils closely inductively coupled to each other and to said abs0rption coil, said two coils being oscillator coils connected With the plate and grid elements respectively of the audion tube to provide the oscillation producing circuits, and an inductively coupled output circuit connected With the plate circuit of the tube and remote from the aforesaid oscillator and absorption coils. f

2. In a modulated oscillator in accordance with claim l, means for varying the` amount of absorption in the absorption circuit coin- ;prising a condenser connected in series in said absorption circuit.

In testimony vwhereof I hereunto affix my signature. Y

FRANCIS J. MEADE. 

